How many members have a full pie next to their name? And how does one achieve such an accolade?

An excellent question and I hope the powers that be will let us know. I'm not sure I've seen a full pie, but the more complete seems to be based primarily on participation: how active someone is on the hotline (asking and answering); how many recipes have been submitted generally (i.e., to contests and otherwise); and how many contests have been won by a contribution. While I haven't seen full pies, it is clear there is a "senior" level that some have achieved that allows an individual to be designated a "recognized authority on [blank]"; I'd be interested in how that is achieved as well.